I kept the subject generic so others can add their own issues. So far my discovered items are tuner-related, but I didn't encounter these prior to firmware v14.
Tuner doesn't allow editing of fingers. If I want to change LMOO to MMOO I can't because whenever I click any of the finger buttons they don't react. I can change modifier keys and specify what keystrokes I want sent, but not which of my 4 fingers I want to use to do so.
Tuner: If I turn on the NUM or SHIFT filter (I couldn't test ALT or CTL) and then delete items tuner doesn't show the items as removed. Instead they still show on the screen. If I go to the next page and back again the lines are still there. If I turn off the filter the removed items will no longer be shown in the list. Tuner will correctly update the cfg file even if the items were still showing on the screen, so this is more of a 'cosmetic' bug.
Tuner: Edited items cannot be deleted when a filter is turned on. Tested with NUM and SHIFT.
Tuner: If I change an entry from s, for example, to alt-s and then activate the alt filter, alt-s won't show in the filter results. After turning off the filter alt-s is listed as s, which is what it originally was. I haven't tested if it saves correctly.
Tuner gives an error if I try to convert a v4 cfg to v5. This might not be new as in firmware v13 the tuner would ignore me when I tried the same thing. The error message is new, however. I only have 1 v4 cfg to test this on.